Question

if the equation 2x^2+bx+8 has equal roots ,find the value of b

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Answer 1

Answer:

The roots of a quadratic equation ax^2 + bx + c = 0 are real if b^2 - 4ac >= 0 .

The equation 2x^2 - bx + 8 = 0 has real roots if (-b)^2 - 4*2*8 >= 0

=> b^2 >= 64

=> b >= 8 or b <= -8

The equation 2x^2 - bx + 8 = 0 has real roots for values of b that lie in the set (-oo, -8]U[8, oo)